html,body{
    width: 100%;
    height: 100%;
}
*{
    margin: 0;
    padding: 0;
    list-style: none;
}
.a{
    width: 100%;
    height: 72px;
    background: #11222E;
    position:sticky;
    margin: 0 auto;
    /* background-color: i; */
}
